Current mode class AB second order filter

A general method for designing class AB translinear filters is proposed. The approach is based on the current mode ‘log filters’ recently introduced by Frey, and combines the idea suggested by Seevinck. The class AB filters are shown to consist of current splitters which inherently map the inputs logarithmically, producing the needed inputs to a pair of log filters, whose exponentiated outputs can be subtracted to obtain the final output.